The scene is where they are about to kill William Wallace. There are several crowd shots during this scene. I believe it is during the part where his dead wife is wandering through the people where this particular extra appears. It is a random woman in the crowd (NOT Wallace's dead wife) that sneaks a look at the camera. She is towards the bottom of the screen (most likely the front of the crowd) standing next to another slightly older woman. I believe they are close to the right hand side of the screen. It's rather annoying because it was so unprofessional of the extra. She does it twice, and it's just a glance looking slightly up and to the side, so you can tell she knows she isn't supposed to be looking.